1. Field of the Invention
The present invention relates to a sealed housing for a field emission display (FED), and particularly to a sealed housing having walls made from Kovar alloy and Cr-doped Kovar.
2. Description of Related Art
Flat panel displays have recently been developed for visually displaying information generated by computers and other electronic devices. These displays can be made lighter in weight and require less power than conventional cathode ray tube displays. One type of flat panel display is known as a cold cathode field emission display (FED).
A field emission display uses electron emissions to illuminate a cathodoluminescent display screen and generate a visual image. A typical field emission structure includes a face plate where the display screen is formed, and an opposite base plate having emitter sites. The base plate also includes the circuitry and devices that control electron emission from the emitter sites.
The emitter sites and face plate are spaced apart a small distance to enable a voltage differential to be applied therebetween, and to provide a gap for electron flow. In order to achieve reliable display operation during electron emission, a vacuum of the order of 10xe2x88x926 Torr or less is required. The vacuum is formed in a sealed space contained within the field emission display.
The use of getter materials in field emission displays to provide adequate vacuum conditions is known in the art. Referring to FIG 2, U.S. Pat. No. 5,688,708 discloses an FED 100 which includes an anode 102 having a plurality of cathodoluminescent deposits 104, a cathode 106 including a plurality of field emitters 108, and a plurality of side members 112 which are positioned between the anode 102 and cathode 106 for maintaining a predetermined spacing therebetween. The side members 112 are affixed to the anode 102 and the cathode 106 by using a glass fit sealant. The inner surfaces of the anode 102, cathode 106 and side members 112 define an interspace region. The FED 100 further defines a plurality of receptacles 118 which are in communication with the interspace region. First and second getter materials 120, 122 are contained in the different receptacles, respectively. The first and second getter materials 120, 122 enhance the vacuum level by adsorption of residual gas molecules in the interspace region. However, the FED 100 takes up more space because of the plurality of receptacles 118. In addition, the protrusions of the receptacles 118 must be accommodated during packaging of the display into a system, such as a lap top computer. Furthermore, the glass flit sealant between the anode 102, cathode 106 and side members 112 can potentially fail during the lifetime of the field emission display package, because of the different coefficients of thermal expansion of the anode 102, cathode 106, side members 112 and glass frits.
It is desirable to provide an improved seal for a field emission display (FED) which overcomes the above problems.
An object of the present invention is to provide a sealed housing for a field emission display (FED) which provides a good vacuum seal and which has a structure strong enough to support vacuum pressure.
Another object of the present invention is to provide a sealed housing which extends the lifetime and increases the reliability of an FED contained therein.
A field emission display package in accordance with the present invention comprises an anode plate coated with a phosphor layer, a resistive buffer spaced from the phosphor layer, a plurality of electron emitters formed on the resistive buffer, a cathode plate in contact with the resistive buffer, a silicon thin film, and a sealed housing defining an interspace region. The anode plate, the phosphor layer, the resistive buffer, the electron emitters, the cathode plate and the silicon thin film are received in the interspace region.
The sealed housing comprises a front plate, a back plate and a plurality of side walls affixed to the front plate and the back plate so that the front plate, the back plate and the side walls define the interspace region. The side walls are made from Kovar alloy, which has a composition of Fe 54%, Ni 29%, and Co 17% by weight. To enhance the mechanical support and vacuum condition provided, the sealed housing further comprises inner walls made from a getter material which function as a mechanical spacer and stabilizer, and which also provide a very strong gettering effect to adsorb moisture (H2O), oxygen (O2), carbon dioxide (CO2), and other residual gases, thereby providing a longer lifetime and greater reliability of the FED.
Other objects, advantages, and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.